It has been postulated that the primary deficit of the child with Attention Deficit Disorder with Hyperactivity (ADD-H) is a reduced sensitivity to reinforcement and punishment. This hypothesis has been examined in a few studies, with inconsistent results, and there has been virtually no investigation of the effects of contingency manipulation on inhibitory ability. Three studies are proposed here to address these issues: Study 1 will examine the differential effects of Reward and Punishment in ADD-H children and Normals on a test of inhibitory ability. Eighteen young (6-8 years) and eighteen older (9-12 years) ADD-H children and their matched normal controls will be assigned to receive Reinforcement for a successful delayed response, Punishment (response cost) for an impulsive response, or Feedback only on the Delay Task of the Gordon Diagnostic System/GDS. Study 2 will examine and compare the effects of applying contingencies for accuracy vs. latency to response on performance on the Matching Familiar Figures Test (MFF-20). Sixty ADD-H subjects and their matched controls will be assigned to receive one the following treatments: reinforcement for an accurate response, punishment (response cost) for an inaccurate response, reinforcement for a reflective response, punishment for an impulsive response, feedback only or no treatment. Finally, in Study 3, we propose to examine the effects of varying reward: punishment ratios on the Vigilance Task of the GDS. Eighty ADD-H subjects and their matched controls will be assigned to receive reinforcement for correct detections, one of 3 levels of punishment for a false positive response (error of commission), no treatment, or one of 4 possible combinations of reward and punishment. A signal detection analysis of the data will be employed. Anticipated benefits of these studies include a better understanding of the role of sensitivity to reinforcement/punishment in Attention Deficit Disorder with Hyperactivity, and information which may be useful in the design of improved behavioral interventions.